摘要
运用历史资料与实地调查相结合的方法,以多元数量统计为手段确定采样地点,以空间尺度代替时间尺度,确定演替系列,以生态化学计量学为基础探讨了高寒矮嵩草草甸退化演替系列氮(N)磷(P)含量及化学计量学特征,发现:1)高寒矮嵩草草甸土壤全量N、P含量随退化演替程度的加深而呈倒"V"字形变化趋势,速效N、P含量随退化程度的加深呈降低趋势,但土壤草甸全量及速效N/P化学计量学特征则呈现降低趋势;2)地上植物N/P化学计量学特征在整个退化演替过程没有明显的差异。说明高寒矮嵩草群落退化改变了土壤中全量及速效N、P的积累和分解速率,打破了土壤系统养分平衡模式,但并没有明显改变植物地上部分整体的N/P化学计量学特征,因此在退化演替过程中植物N/P比为草地退化诊断的惰性指标;土壤N/P化学计量学特征变化同草地退化演替过程具有较好的同步性,其对草地退化演替的敏感性较高,有可能成为未来草地退化诊断的生态指示指标。
Alpine Kobresia humilis meadows are one of dominant vegetation types in Qinghai-Tibet Plateau. In the past decades, increasing human activities have resulted in dramatic changed in these alpine meadows. As a result, alpine meadows are experiencing different degrees of degradation. The degradation succession stages have been identified as six stations： gramineous grass-Kobresia humilis community, Kobresia humilis community, thickening in mattic epipedon Kobrecia pygmaea community, cracks in mattic epipedon Kobrecia pygmaea community, collapse in mattic epipedon Kobrecia pygmaea community, and forbs-＂ black soil beach ＂. Kobresia humilis alpine meadows degradation processes involved variations in soil elements and community structure and composition. Ecological stoichiometry has been developed to understand the relationships between organisms and ecosystem structure and function. Because nitrogen （N） and phosphorus （P） are the two most important elements limiting plant growth in a variety of ecosystems, biomass N ：P stoichiometry is most used in this respect. In this study, we investigated N/P ratios of soil and plants in a degradation series of the Kobresia humilis alpine meadows in Qinghai-Tibetan Plateau. Furthermore, we analyzed the relationships between of the key factors to affect community succession process and N/P ratios of plant and soil. We found that total N and total P content of soil decreased firstly and then increased with increasing degradation. The maximum values appeared in the Kobresia humilis community or in the thickening in mattic epipedon Kobrecia pygmaea community. Available N and available P of soil decreased with increasing degradation. Soil N ：P ratio also decreased with the degradation process, and thus the highest soil N/P values appeared in the gramineous grass-Kobresia humilis community. By comparison, no significant difference in biomass N/P ratios were observed at community level among succession stages. This indicates that soil N and P cycling decoupled during gr
出处
《生态学报》
CAS
CSCD
北大核心
2013年第17期5245-5251,共7页
Acta Ecologica Sinica
基金
国家自然科学基金重点项目(41030150)
国家自然科学基金面上项目(31270576)
中国科学院战略性先导科技专项(XDA05050404)
国家科技支撑计划课题(2012BAC08B06)
关键词
生态学化学计量学
氮磷比
高寒矮嵩草草甸
退化演替
Ecological stoichiometry, N/P ratio, Kobresia humilis, degradation succession process
